In this paper, we prove that if a delay differential equation with impulse effects of the form x (t) = A(t)x(t) + B(t)x(t − τ) , t = θ i , ∆x(θ i) = C i x(θ i) + D i x(θ i−j), i ∈ N, verifies a Perron condition then its trivial solution is uniformly asymptotically stable.

In this paper, we obtained some necessary and sufficient conditions for oscillation of all the solutions of the first order neutral delay difference equation with constant coefficients of the form ∆[x(n)− px(n− τ)] + qx(n− σ) = 0, n ≥ n0 (∗) by constructing several suitable auxiliary functions. Some examples are also given to illustrate our results.

In this article, we concerned with oscillation of the neutral delay differential equation [x(t) − px(t − τ)]′ + qx(t − σ) = 0 with constant coefficients. By constructing several suitable auxiliary functions, we obtained some necessary and sufficient conditions for oscillation of all the solutions of the aforementioned equation for the cases 0 < p < 1 and p > 1.

A delayed SIR epidemic model with a generalized incidence rate is studied. The time delay represents the incubation period. The threshold parameter, R0(τ) is obtained which determines whether the disease is extinct or not. Throughout the paper, we mainly use the technique of Lyapunov functional to establish the global stability of both the disease-free and endemic equilibrium.

In this paper, we consider the nonlinear delay dynamic system x(t) = p(t)f1(y(t)), y (t) = −q(t)f2(x(t− τ)). We obtain some necessary and sufficient conditions for the existence of nonoscillatory solutions with special asymptotic properties of the system. We generalize the known results in the literature. One example is given to illustrate the results.

In this article, existence of multiple positive T -periodic solutions for the first order delay difference equation of the form ∆x(n) = a(n)g(x(n))x(n) − λf(n, x(n− τ(n))) has been studied. Leggett-Williams multiple fixed point theorem has been employed to prove the results, which are established considering different cases on functions g and f .

In this paper an oscillator with time delayed velocity feedback controls is studied in detail. The particular attention is focused on internal double-Hopf bifurcation with an external exciting force. Linear analysis is used to find the critical conditions under which a double-Hopf bifurcation occurs. Then center manifold theory is applied to obtain an ODE system described on a four-dimensional ...

New oscillation criteria for the second order nonlinear neutral delay differential equation [y(t) + p(t)y(t− τ)]′′ + q(t) f(y(g(t))) = 0, t ≥ t0 are given. The relevance of our theorems becomes clear due to a carefully selected example.